Octopus and Starfish

As nouns the difference between octopus and starfish is that octopus is any of several marine molluscs/mollusks, of the family Mollusca, having no internal or external protective shell or bone (unlike the nautilus, squid or cuttlefish) and eight arms each covered with suckers while starfish is any of various asteroids or other echinoderms (not in fact fish) with usually five arms, many of which eat bivalves or corals by everting their stomach. source